Fluid-pressure brake for electric cars



Patented Mar. 3, 1925.

UNITED STATES HARRISON S. SWEET, OF UTICA, NEW YORK.

FLUID-PRESSURE BRAKE FOR ELECTRIC CARS.

Application filed January 24, 1923. Serial No. 614,691.

To all 101mm/ t may concern.'

Be it known that I, HARRISON S. SWEET, a citizen of the United States,residing vat Utica, in the county of Oneida and State of New York, haveinvented certain new and useful Improvements in Fluid-Pressure Brakesfor Electric Cars, of which the following is a specification, referencebeing had therein to the accompanying drawing.

My invention relates to a fluid pressure brake for electric ears, and Ideclare'the fol# lowing to be a full, clear, concise and exactdescription thereof sutlieient to enable anyone skilled in the art towhich it appertains to make and use the same, reference being had to theaccompanying drawings in which like reference characters refer to likeparts throughout the specification.

The object of the invention is to add an air conserving device to asafety brake equipment which applies the brakes automatically whenmanual pressure is* removed from the electric power controller handle asdescribed in my former application filed in the United States PatentOffice, January 13, 1922, and numbered serially 528,894.

I-Ieretofore, in safety control systems using compressed air, it wasnecessary to build up the brake cylinder pressure to main reservoirpressure upon opening the air koperated doors of the car. This oldmanner of applying the brakes consumes more compressed air than isnecessary for the Vreason that in the ordinary braking of the car thereis a relativelysmall pressure in the brake cylinder when thercar isbrought to a stop. For safe operation, however, it is necessary only tohave a predetermined pressure in brake cylinder when the car is stopped.This pressure does not have to be equal t main reservoir pressure.Therefore, in this system the pressure in the brake cylinder is built upand maintained, when car has come to a stop, to some predeterminedpressure which is considerably less than, main reser voir pressure,although sufficient to hold car stationary. Such a predeterminedpressure is adapted to a quicker release of the brakes, owing to thelower pressure in the brake cylinder than would be the case, asheretofore, where the pressure in the brake cylinder is built up to mainreservoir pressure. Furthermore, thisreduction of pressure in the brakecylinder saves not only in pressure of air in said cylinder but also inthe volume of air in brake cylinder, thereby economiz ing in airpressure used at each regular stop of the car at which it is necessaryto open the doors for the egress and ingress of passengers. f

` Moreover', the decrease in pressure of air in b `ake cylinder, reducesthe travel of the piston in the brake cylinder, whereby there resultsless wear on the brake rigging.

Furthermore, the system allows the car to be operated independently ofthe emergency brake and door control features until pressure is builtupin main reservoir to a predetermined degree, after which, the emergencybrake and door operating mechanisms are automatically cut in. In theevent the main reservoir pressure of the system falls below thepredetermined degree, the brakes will be applied automatically, thepower cut olii, rails sanded and the doors balanced.

The object will be understood by referring to the drawings in which thefigure represents. a diagrammatic view of the device, showing parts insection and other parts in elevation.

Referring more particularly to the drawings, the main reservoir l isconnected to the well known motormans brake valve 2 by pipe 3. Valve 2has leading therefrom exhaust pipe et that opens to at-mosphere andstraight air pipe 5. Pipe 5 connects with emergency valve casing 6 andis adapted to be united by port 7 formed in the upper part 8 of movablepiston valve 1() to pipe 11 that leads to brake ycylinder 12. Theturning of handle to release position or tothe left of center, as shown,will close main reservoir pipe 3 and connects straight air pipe 5 topipe 4, whereby to exhaust brake cylinder 12 to atmosphere in order torelease the brakes. "When handle 15 is in center or lap posit-ion, pipes3, i and 5 are closed. IIowever when handle 15 is to the right of centeror application position, main reservoir pipe 3 is connected to'pipe 5and pipe 4 is closed, whereby a direct application of the air brakescanbe effected, provided piston valve 10 is in up position asillustrated in the figure.

Main reservoir pipe 3 is connected also to protection valve casing atport 21. Said protection valve embodies movable piston valve 22 havingan open chamber at 22a and is held against seat 23 by coiled spring 24.In this position of piston valve 22, port 21 is closed and port 27 isvented to atmos- CIK phere through port 25, wherebyto eXhaustpipe 26lconnected to casing 2() by way of port 27 that leads to the interior 28of cas ing 20. Pipe 26 is united to cross pipe 29 that joins with pipe`30 leading .to .einergency valve casing 6. Pipe 26 is united also tostraight air pipe 5 at 32,-therebeing interposed a one way rech-argecheek valve 33 and a reducng bushing 34.

Protection-valve casing 20 is connected by pipe 35 withemergency tankreservoir 36. Pipe 37 leads from pipe 35 .to port- 38 formed inemergency valve casing 6. Pipe will be connected to pipe 35andeinergency reservoir 36 when the pressure entering chamber 22a atport 21 reaches a predetermined degree lat which spring 24 kwill yield.In th-'s event piston valve 22 willbe forced against the tension of saidspring24 oif from. seat to seat 39. In thisposition of valve 22, portl'27 of casing 2O will be closed to prevent the .further exhaustion ofpipe 26.

y The emergency valve embodies the aforesaid casing 6 having a port 4.6that leads from port 3S.to the chamber 41 abovefpiston valve10 and a`port 42 that leadsfrom said port 3S to chamber 41 below piston valve 1()when in up position. A reducing bushing 43 which is made Aremovable toa'l low for varying the sizeof the aperture is inserted in line withport .42.

`When emergencypi'ston valve .10 isin up position7 as shown in fulllines, pipe is connected to piper11 of brake cylinder 12 by means ofport 7, whereby to permit .a= direct application or release of thebrakes, .in .accoi-dance with the position of handle 15. Moreover, pipe51 `will be` closed .and pipe 54 leading to tank 56 isconnectedtochamber 41 to supply air pressure to operate front doorengine v and rear ldoor` engine 61, which, in turn, actuate therespective doors ofthecar, .as .more fully. `explained in said formerapplication.

lVhen piston valve lOisforced-.off valve stop 45 to lower position onseat 46, an excess of compressed air inchamber 41 above piston valve 10,and against the tensionof spring 47, port 42 will .open into chamber 41above piston valve 10. In this latter posit-ion of valve 10pipe V30willbe shut oif. Port 50, formed in the upper part S of movablepistonvalve 10` will connect also in this latter or down. position. of valve10, pipe .51, which leads to electriccircuit knock oif engine 52 andpipe 53 havingreducing bushing 53a therein to sander,.not shown, andpipe 54 thatleads to kpipe 'to reservoir tank 56 adapted to actuate saidelectric circuit knock olf engine 52:1.and sander, not shown. Therefore,in this lower position of piston valve 10, the portsawould be incondition to allow the. compressed, air toeil'ectan emergency7application ofthe brakes .as well yasto actuatethe electriccircuit-knock off engine 52a to off posftion and to actuate the sander,not shown.

The lower part of chamber 41 is connectedfbyaport64 to pipe 3() thatruns to thepilot valve casing 65 containing a valve 466. Valve 66embodies seats 67 and 68 connected by .a shaft 7.0 having allongitudinal groove 71 therein for the escape of coinpressed air fromchamber 7 2 to chamber 7 3, when valve 66 is in open position. A plunger7 6 havinga shoulder 77 makes contact with the lower-surface of valve66. Said plungeii76has a -groove A81 formed therein for the passageof.compressedair,to atmosphere at fall'tin'ies. Plunger T6 isadapted torest .upon the upper surface of leverlI` as shown and'described in saidformer 'application, -which lever S1 is fulcrnmed at 8.2. .The Vfree endvof lever -81fisheld elevated yby a conically woundcoiled lspring 83that is disposed about shaft 84and rests between the upper surface .ofcasing 65 yof the pilot valve and the lower surface of lever 81a that isequipped Vwith a kflange S5 for. retaining spring 83 in position. Ashouldered pin 86 is mounted te move freely iu acorrespondingly formedrecess 67 in casing 65. The lower end .of pin S6rests on the upper.surface of lever 81a, whichholds pin 86 inelevatedposition. The upperend of pin 86, however, rests against the lower surface of controllerhandle casing` 88 and, thereby, holds the handle 90 yieldingly inelevated position. 4Said casing 88 is fulcrumed to swing on rod 9 1supportedon casing65. .lllhen handle 9() isinelevated position, valveseat' 67 will be unseated and allow compressed air topass from chamber72tol chamber 7 3 and thence through aport 91a.to the yunderside of ballvalve 9,2 to chamber 93..'thereabove, port 94 topipe 9,5 to valve casing96. Compressed air will "flow also though ina smaller quantity becauseof reduced passagewayz97 to pipe 9S to front door engine operator 62,whereby to .actuate the Vfront Vdoor to open position, as shown andVdescribed in said former application.

Compressed air will "flow also, although in a' small quantity,throughby-pass 99 having a reduced passageway at 100 to the under side of ballvalve 103 to pipe y104 to rear door engine operator 62a, to open therear door, not shown.

Valve casing 96, which contains movable pistony valve 110anddifferential check valve 111, although .any well known feed valve may be.substituted inplace ofdifferential check .valve 111, is to conserve theair pressurerequiredto operate the system and to prevent .an emergencyapplication of the brakes upon release of controller handle 96, if lapredetermined pressure has been built up already in brake cylinder 12.Casing'96 is equipped with two or more port holes112,

112, opening to atmosphere. Movable piston valve 110 has formed in oneend an open chamber 115 and a passageway for the projecting end 116 ofdifferential check valve 111. End 116 is grooved at 117 to permit thepassage of compressed air from chamber 115 to chamber 118 and to port119 in valve 110 to chamber 120 of casing 96 on the side of valve 110beyond chamber 115. Chamber 120 is connected to straight air pipe 5 bypipe 121.

Movable piston valve 110 is held to seat 122 by a small pressure inchamber 120 against a higher pressure entering by way of pipe 95 becauseof the difference in size of the diameters of the respective chamber 120of casing 96 and chamber 115 of valve 110.

Moreover, piston valve 110 carries therein said differential check valve111 which is held seated at 125 by spring 126. The tension of spring 126is adjusted to allow compressed air to force `valve 111 from its seat125, whenever the diiference of pressure in chamber 115 from chamber 120is sufficient to overcome the adjusted tension of spring 126. v

The operation of the system is effected by first starting the air pump,not shown, which forces compressed air into main reservoir 1. Theoperator should press down now on handle 90. As the pressure builds upin the system, it will flow also through pipe 3 to protection valvecasing 20 to chamber 22n formed in the end of movable piston valve 22.lVhen this pressure in chamber 22*l has reached the predeterminedpressure at which spring 24 is adjusted, piston valve 22 will be forcedfrom seat 23 to seat- 39, thus closing pipe 26 to atmosphere andconnecting pipe 3 through chamber 22a in casing 2O to pipe 35, toemergency tank 36, pipe 37, port 38, where it divides, part going by wayof port 49 to chamber 41 above piston valve 10 and part going by way ofport 42, that has reducing` bushing 43, therein, to chamber 41 belowpiston valve 10 and thence to passageway 64 to pipe 30 to pilot valvecasing 65 to chamber 72 therein. If handle is in lower position, passageto chamber 73 is closed.

The pressure. will pass also from chamber 41 in emergency valve casing 6by way of pipes and 55 to tank 56 and thence through pipes 55 to pipe55A to door enlgines 60 and 61 to close the doors, not shown, if notalready closed. The car is ready then for operation. However, should theoperator start the car before sufficient pressure is built up in thesystem to force piston valve 22 to seat 39, the brakes may be applied bymanipulating handle 15 to application position, thereby, connecting mainreservoir pipe 3 to straight air pipe 5, so that the direction of theair pressure will be from main reservoir 1 to pipe 3, brake valve 2,pipe 5 to port 7 formed in the upper part 8 of movable piston valve-10to pipe 11 to brake cylinder 12 thus applying the brakes. Although, inthis instance, the passage through recharge check valve 33 is portedto'atmosphere, reducing bushing 34 being relatively small will retardthe escape of air pressure sufficiently to allow for the application ofthe brakes.

Furthermore, since the pressure has built up on both sides of pistonvalve 10 the saine will remain in full line position as illustrated andthe brakes can be applied or released from brake valve handle 15 asheretofore explained.

Operator by now applying the brakes from handle 15 will bring the car toak stop. In doing this, most of the pressure in brake cylinder 12 andpipe 5 will be exhausted, if

a smooth stop is effected, and, yet,`suliicient pressure will beretained to hold the car stationary. By now leaving brake valve handle15 in lap position, with all ports closed, thereby, closing pipe 5, thesmall amount of pressure left in pipe 5 and chamber 120 of valve casing96 will hold piston valve 110 on seat 122 even though full reservoirpressure is applied by way of pipe and chamber 115. If now, with piston110 on seat 122, operator releases handle 90, thereby, allowingcompressed air to flow from chamber 72 to chamber 73, to port 91a topassageway 97 to pipe 98 to front door kengine operator 62, whereby toactuate said front door, not shown, to open position.l The pressure willflow also up by ball valve 92 to chamber 93 thereabove to by-pass 99 topipe 104 to rear door engine operator 62L to open the rear door, notshown. rThe pressure will fiow also through port 94 to pipe 95 to valvecasing 96 to chamber 115 in valve 110. As

piston valve 110 is held on seat 122, the

pressure will build upr door operating pipes 98 and 104, whereby to movethe pistons of operators 62 and 62n outward to open the doors, as fullyset forth in said former application. y

Handle 15 of brake valve2 being still in lap position, with all portsclosed, no pressure will be supplied to pipe 5. However, thisy pressurein pipe 5 will be built up and maintained from pipe 95 throughdifferential check valve 111, whenever, the difference in pressurebetween chamber 12() on the far side of movable piston valve 110 andchamber in valve 110 falls below that at which spring 126 is adjusted.Inasmuch, as passageways 97 and 100 are small and the rate of flowthrough port 119 in valve110 is low, bushing 43 in emergency casing 6isv of such size that it will supply sufficient pressure to chamber 41below emergency valve 10, port 64, pipe 30 to maintain a given pressurein chamber 41 below valve 10,

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whereby'this same pressure together with the tension of `spring 47 willhold piston valve 10 in full line position shown to prevent an emergencyapplication ot the brakes.

5 It handle 90 is pressed down, now, piston valve @Savill shut ofi' thesupply'o't compressed air to chamber 73 and will vent saidl chamber 73to atn'iosphere by way of the groove 81 in plunger 7G, thereby, allowingl@ the pressure in pipe 98 to `flow back through reduced passageway 9Tto port 91a to chamber 7 3 to chamber 74 to atmosphere to close thefront door. In this instance, pressure in pipe, 104 will be maintainedto hold open rear door, as ball check valve 92 prevents the pressurefrom flowing therepast to channel 91a. Any leakage is supplied throughbushing 10G to pipe 104, as-explained in said former application.

then the operator moves handle 15 of brake valve 2 to release positionto release the brakes, air pressure will be eX- hausted from pipe 5 andchamber 120 of valve casing 99, thereby allowing the pres- 5" sure inchamber 11'5 to force piston valve 110 ofta :from seat 122 and allowcompressed air to iow from pipe 95 to atmosphere, thereby exhausting thecompressed air from pipe 104 by way oit' ball valve 103 to pipe 3") 95to casing 96 to holes 112to atmosphere,

whereby to close the rear door.

Should the operator release handle 90, while operating the car, withoutfirst applying the brakes and should there be no G" pressure 1n chamber120, compressed air willbe free to pass through pipe 30, chamber T2 ofpilot valve casing G5, chamber 73, passageway 91a, ball valve 92,by-pass 94, pipe 95, chamber 115 formed in valve casl'l ing 96, ports112 to atmosphere.v Since this rate of iiow is highL whencompared to theamount of pressure that can pass through reducingl bushing 43 ofemergency valve casing 6, the pressure in chamber 41 under piston 10will be reduced to such a degree,

that the pressure thereabove will overcome the combinedpressure andtension of spring 47, whereby, to -force piston 10 to lower seat 4G toeffect an emergency application of 5@ thelbrakes. In thisv lowerposition of valve the electric power and to sand the rails.

Immediately the pressure inv tank G has reduced itself suiiiciently, thedoors, not shown, of the car will be balanced and may be pushed openthereafter. The same result @5 will obtain if the operator atter openinguses-14@ the doors, moves brake valve handle 15 lo release positionbefore pressing downou.

holes 112 to atmosphere. 1n order to causev spring47 to torce pistonvalve 10 upiagainst` stop 45 to release the brakes, itfis necessary tobuild pressure up in chamber 41 below piston valve to nearly reservoirpressure. This is accomplished by iirstpressing down on pilot valvehandle 90 and then moving brake valve handle t0 application position,whereby, pressure is-it'ree to flow main reservoir pipe 3,.brake valvepipe 5, bushing 34, one way cheek valve 33 to pipe 26, to pipe 29 topipe 30, port (34. to chamber 41 below piston valve 10. lmmediately thispressure has been built up to nearly reservoir pressure,- spring 4T willforce pist-on valve 10 up to ttullline position shown, wherebyto-connectf pipe. 11 of brake cylinder 12 to pipe 5 to permit thepressure in said brake. cylinder 12 to exhaust toatmosphere in order torelease the brakes when brake valve handle 15is turned to releaseposition. Port 42 being now belowpiston:valve 10 the compressed air willmaintain the required pressure in chamber 41, whereby to allow spring 4?to.y holdy valve 10 in up position against' stop` 45.

Vhenever. the pressure in main reservoir 1, pipe 3, port 21 and chamber2S ot'valve casing on nonspring side ot" piston` Jfalls below apredetermined degree at. which spring` 24iis adjusted, piston 22 willbe. forced by said spring 24;y from seat 39 to seat 23, thus .portingypipe 2G 1 to atii'ios} ilio1ethrough port 25, whereby to allow thepressure to flow from chamber 41 beneath piston. valve 10 faster than itissuppliedby way ot' reducing bushing This will result in an emergencyapplication 0f the brakes inthe same manner aswhenhandle 90 is released.

In order to agaiir release the brakes. as pipe 2G now flowsto=at1nosphere and the pressure supplied through bushing 34v can flowalso to atmosphere, it is necessary toexhaust the pressure in emergencytank 36, which can be effected by opening cock 130 or4 by building uppressure in main reservoirl 1 sufficiently to overcome spring tension onpiston'valve 22 to force it to seat 39,. thus closing portto atmosphere`whereupon the brake-s can be released as heretofore described.

Having thus described my invention what I claim as new and desire tosecure ters Patent is:

l. In a fluid pressure brake for electric cars, an emergency valve, anemergency reservoir adapted for supplying fluid under pressure to saidemergency valve, a main reservoir, means for supplying fluid underpressure to said emergency reservoir from said main reservoir, and meansfor conserving the pressure in said system.

2. In a fluid pressure brake for electric cars, an emergency valve, anemergency reservoir adapted for supplying fluid under pressure to saidemergency valve, a main reservoir, means for supplying fluid underpressure to said emergency reservoir from said main reservoir, whenpressure in the main reservoir is above a predetermined degree, andmeans for stopping this supply by Letof fluid under pressure when thepressure in main reservoir falls below some predetermined degree.

8. In a fluid pressure brake for electric cars, an emergency valve forveffecting an emergency application of the brakes, an emergency reservoirfor supplying pressure to said emergency valve to operate said brakes, amain reservoir, means for supplying pressure to said emergency reservoirfrom the main reservoir, when the pressure in said main reservoir isabove a. predetermined degree, and means for stopping this supply andfor ell'ecting an emergency application of the brakes when the pressurein main reservoir Jfalls below a predetermined degree.

4. In a fluid pressure brake for electric lars, means for automaticallyapplying the brakes, a brake cylinder, means for preventing theautomatic application of the brakes by an application of predeterminedpressure, and means for building up pressure in said brake cylinder to apredetermined pressure.

5. In a fluid pressure brake for electric cars, a spring pressed pilotvalve handle for automatically applying the brakes of the car, a valvefor preventing this automatic application of the brakes, by a brakeapplication of a predetermined pressure, a brake cylinder, and means forbuilding up and maintaining pressure in brake cylinder at anotherlpredetermined pressure upon release of said pilot valve handle.

6. In a fluid pressure brake for electric cars, a spring pressed pilotvalve for automatically applying the brakes of the car, when manualpressure is removed from the same, a valve for preventing this automaticapplication of the brakes, a brake cylinder, and a feed valve forbuilding up and maintaining a predetermined pressure in said brakecylinder upon release of said pilot handle.

7. In a fluid pressure brake for electric cars, a brake cylinder, anemergency pipe, a valve for controlling the pressure in said emergencypipe, and means for oper-ating the doors of the car by pressure in theemergency pipe. y

S. In a fluid pressure brake for electric cars, an emergency pipe, meansfor controlling pressure in the emergency pipe, and means, whereby thepressure in the emergency pipe will maintain a suitable pressure inbrake cylinder.

9. In a fluid pressure brake for electric cars, a brake cylinder, anemergency pipe, a valve for controlling the pressure in said emergencypipe, and for maintaining a Asuitable pressure in said brake cylinder.

l0. In a fluid pressure brake for electric cars, a brake cylinder, anemergency pipe, a valve for controlling the pressure in the emergencypipe, and for maintaining'a suitable pressure in the brake cylinder, andmeans for operating the doors of the car by pressure inthe emergencypipe.

11. In a fluid pressure brake for electric cars, having a brakecylinder, any emergency pipe, a valve for controlling the pressure insaid emergency pipe, whereby to effect an emergency yapplication of thebrakes, a straight air pipe adapted to be connected to said brakecylinder, a pilot valve adapted to vent pressure from said emergency airpipe, means for controlling the pressure in said emergency pipe, wherebyto prevent an emergency application of the brakes, and to maintain apredetermined pressure in said straight air pipe upon release of saidpilot valve.

12. In a fluid pressure brake for electric cars, an emergency valvecasing containing a valve, a pipe leading from said casing, a brakecylinder connected to said pipe, said emergency valve adapted to effectan emergency application of the brakes, upon a reduction in emergencypipe pressure, a straight air pipe adapted to be connected to said brakecylinder, a pilot valve controlled by a controller handle, whereby tovent pressure from the emergency pipe upon release of said controllerhandle, another valve for controlling the pressurein the emergency pipe,whereby to prevent an emergency'application of the brakes, and saidvalve adapted for maintaining a suitable pressure in the straight airpipe upon release of said controller handle.

13. In a fluid pressure brake for electric cars, an emergency pipe. avalve Jfor controlling pressure in said pipe, whereby to effect anemergency application of the brakes, door operating motors, al pilotvalve controlled by a spring actuated handle. whereby to vent pressurefrom said emergency pipe, a straight air pipe, means for effecting apressure in said straight air pipe, whereby to prevent an emergencyapplica- SOV ice

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tion of the brakes, means vfor maintaining a predetermined pressure insaid straight air pipe, upon release of said pilot controller handle,door operating motors, and pressure means for operating said motors`synchronously, whereby to actuate the doors.

1.4. In a fluid pressure brake for electric cars, having an emergencypipe, a valve for controlling pressure in said pipe, whereby to eect anemergency application of the brakes, a straight air pipa-whereby toeffect a direct application of the brakes, a pilot valve actuated by acontroller handle, whereby the release `of said handle will actuate thepilot valve to vent pressure from the emergency pipe, means whereby apressure in the straight airpipe will control pressure in the emergencypipe to prevent an emergency application vof the brakesand said last"named means adapted for building up and valve, `whereby a lreduction inpressure :in vsaid pipe willefiect an emergency applicavtion 'of thebrakes, a straight air pipe, a pilot vvalve governed by apowercontroller handle,

whereby to vent pressure from the einer- `gency pipe, another valve,whereby thepressure in the emergency pipe will be controlled bypiessurein straight -airpipe to prevent an emergency ,application of the brakes,and said valve adapted for building up and maintaining a predeterminedpressure inthe straight air pipe upon release of saidpowercontroller.handle V16. In a fluid pressure brake for electric cars,having a power controller handle/an emergencypipe, abrake cylinder, avalve for controlling the admissionfand escape of pressure to saidcylinder, whereby a reductionin pressure in said emergency pipewilleffect an emergency Yapplication fof the brakes, la `straight airppe, apilot `valve actuated by the power controller handle, whereby therelease of the power Vcontroller handle will ventpressure Yfrom saidemergency pipe, another valve for controlling the pressure intheemergency pipe, whereby Yto prevent anemergency application of thebrakes, ,anida third valve for building up andinaintaining `apredetermined: pressure in said istraight,airlpipe\upon release'of said,power eontrollervhandle.

17. vIna fluid pressure brake for electric cars having a. powercontroller handle, a

brake cylinder, an emergency air pipe, an

emergency valve adapted to be governed by pressure in saidpipe, wherebya reduction in pressure in saidpipe willeii'ectan emergency applicationof the brakes, astraight air-pipe, a second valve actuated by `saidpower controller handle, whereby the release of said power controllerhandle will vent pressure from said emergency pipe, a third valve forcontrolling the pressure in said emergency pipe, whereby to preventanemergencyapplication of the brakes, and a fourth valve for building' upand maintaining a predetermined pressure in said straight air pipe uponrelease 0f the power controller handle.

18.111 a fluid pressure brake for electric carshaviiig a powercontroller handle, an emergency valve adapted to effect an einergencyapplication of the brakes, a `straight air pipefor effecting adirectapplicaton of the brakes, a second valve for automaticallyapplyingthe brakes when the pressure in said system falls below aypredetermined level,l and means for conserving the pressure insaidsystem.

19. In a fluid pressure brake for electric cars, having a powercontroller handle, an emergency valve adapted to effect anen'ier- `gencyapplication of the brakes, a straight air pipeor effecting :a directapplication of the brakes, asecond valve for automatically applying thebrakes when pressure in said system falls below a predetermined level,and a third valve for conserving the pressure in said system.

20. 'In a .fluid pressure brake for electric cars, having a powercontroller handle, an emergency valve adapted to efiect an einergencyapplication of' the brakes, a straight air pipef'or effecting a directapplicationvol the "brakes, means lfor automatically applying thebrakeswhen the pressurein sai-d systein falls below a predeterminedlevel, and other means for conserving the =pressure in said system.

21.111 a fluid pressure brake system for electric cars, automatic meansfor lapplying' the brakes and a piston valve for conserving the pressurein said system.

In testimony whereof 'l havealiixed my signature.

.HARRISON S. SWEET.

